The present invention relates generally to magnetic data storage and retrieval systems. More particularly, the present invention relates to an edge barrier for prevention of spin valve sensor corrosion and improvement of spin valve sensor reliability.
A transducing head of a magnetic data storage and retrieval system typically includes a magnetoresistive reader portion for retrieving magnetic data stored on magnetic media. The reader is typically formed of several layers which include a magnetoresistive (MR) sensor positioned between two gap layers, which are in turn positioned between two shield layers. The MR sensor may be any one of a plurality of MR-type sensors, including, but not limited to, AMR, GMR, VGMR, spin valve and spin tunneling sensors.
During fabrication of the transducing head, the MR sensor is subjected to many processing steps. Current contacts and biasing layers are commonly deposited adjacent to the MR sensor after the MR sensor is shaped, but before the second half gap is deposited. The formation of the contacts and biasing layers, as well as the patterning of the MR sensor itself, subjects the MR sensor to a harsh environment that may result in corrosion of the MR sensor. This is particularly true of a multi-layered sensor such as a spin valve sensor. Multi-layered sensors generally are formed of multiple materials, several of which very easily corrode. Since an MR sensor relies on the existence of each of its layers to operate properly, corrosion of any of its layers will result in the sensor having a reduced amplitude, a distorted signal output, decreased stability, and/or increased noise.
Accordingly, there is therefore a need for a means of preventing corrosion of the sensor in a transducing head.
The present invention is an edge barrier of corrosion-resistant material for preventing corrosion of a sensor of a transducing head during fabrication of the transducing head. In a transducing head of a magnetic data storage and retrieval system in accord with the present invention, the transducing head has a bottom shield, a first half gap positioned on the bottom shield, a sensor layer positioned on the first half gap, a second half gap positioned on the sensor layer; and a top shield positioned on the second half gap.
The sensor layer includes a magnetoresistive sensor having sidewalls and a barrier surrounding and in direct contact with the sidewalls of the magnetoresistive sensor. An acute angle formed between the sidewalls of the magnetoresistive sensor and the first halfgap preferably is in the range of about 40xc2x0 to about 90xc2x0. The barrier is preferably formed of a corrosion-resistant material such as Ta, TaN, W, Cr, Al2O3, SiO2, or NiFe.